Technical Field
The present invention relates to a preparation method of a degradable composite material and applications thereof, particularly to a preparation method of a composite material prepared by using a film coating technology and applications thereof, which belongs to the field of composites.
Description of Related Art
In order to prevent liquid to freely seep into paper materials, paper food containers, an anti-seeping, leak-proof, water-proof and humid-proof paper containers and garbage containers, paper diapers and sanitary towels are usually coated with a plastic film on the inner and outer surfaces to achieve the waterproof and leak-proof effects. Polyethylene (PE) or polypropylene (PP) is usually used as the raw materials during film coating. Paper tools coated with films have waterproof and leak-proof effects. However, PE and PP cannot be biologically degraded and generate a vast amount of white garbage, polluting environment.
In order to solve the problem of plastic pollution, a PLA (polylactic acid) coating paper has been developed in the industry. The PLA can be naturally degraded, and is non-toxic and environmentally-friendly, but the PLA is greatly limited in application scopes because of its disadvantages such as brittleness, toughness, impact resistance and thermal stability. Moreover, the current PLA coating technology has a certain limit in the thickness of coated film. The thickness of the PLA film cannot be smaller than 22 g/m2, causing high cost to the PLA film. Another biologically degradable material PBS (poly(butylene succinate)) features low processing temperature, low viscosity and poor melting strength. In addition, PLA and PBS are crystalline polymers, and products thereof usually have a certain brittleness. Therefore, the PLA and PBS are greatly limited in the application scope in the packing field.
In the present invention, PBAT (poly(butylene adipate-co-terephthalate)) is a copolymer of butylene adipate and butylene terephthalate, which has outstanding ductility and elongation at breaking point and also has good heat resistance and impact resistance. Besides, PBAT is also an excellent biologically degradable material and therefore can be used to improve the mechanical properties of the fatty polyesters such as PLA. “The Study on Super-Fine Calcium Carbonate Filled Degradable Polyester Materials (Plastic, 2009, 38 (3): 69-71, Xiao Yunhe, et al.) shows that the mixing of the PBAT and the calcium carbonate will not only realize complete quick degradation of materials but also greatly save on costs. However, the PBAT has a physical feature of very high viscosity, the PBAT adheres very easily to the equipment during coating operations, causing failure to its continuous production. Therefore, the report of a successful use of the PBAT film is not seen yet.